Refrigerating apparatus



June 10, 1941. M. w. BAKER 2,245,454

REFRIQERATING APPARATUS Filed Sept. 24. 1957 a. lNlV-iNT OR.

- BY 6 I @ZA/ ATTORNEYS Patented June 10, 1941 UNITED STATES PATENT OFFICE I 2,245,454 REFRIGERATING APPARATUS Marshall w. Baker, Dayton, Ohio, assignor to General Motors Corporation, Dayton, Ohio, a corporation Delaware Application September 24, 1937, Serial No. l65,552

11 Claims.

This invention relates to refrigerating apparatus and heat transfer apparatus and more particularly to liquid control means.

.It is a difiicult problem to provide a desirable and satisfactory control for controlling the flow of liquid refrigerant from the liquefying means to the evaporating means in a refrigerating system. This is demonstrated by the fact that so It i another object of my invention to provide a diaphragm operated valve means for a refrigerating system in which both sides of the diaphragm are exposed to refrigerant in the system. I

It is a still further object of my invention to provide a means for preventing'the flooding of the evaporator during idle periods of the compressor when an elongated orifice i employed as a liquid control.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawing, wherein a preferred form of the present invention is clearly shown.

In the drawing:

Fig. 1 is a diagrammatic representation of a refrigerating system including one form of my control means shown insection;

Fig. 2 is a diagrammatic representation of refrigerating system including another form of my control means shown in section.

'Briefly, in the first form of my invention, I

' have shown a'pressure operated valve in series with a restrictor which is biased to closed position by a spring, but opened by the pressure differential existing between the inlet and the outout of the evaporating means to act as a sensitive actuator to close the valve whenever liquid s discharged from the evaporating means. The third form reverses the second form to cause opening of the valve when there is no pressure difference or when liquid is in the cup:'

Referring now to the drawing, and more particularly to Fig. 1,, there is shown a liquefying means including a compressor 20 for,compressing refrigerant and for forwarding the compressed refrigerant to a condenser 22 where the compressed refrigerant is liquefied and collected in a receiver 24. From the receiver 24,. the liquid refrigerant is forwarded through a supply conduit 26 to a restrictor or elongated orifice 28 provided for controlling the flow of liquid refrigerant into the evaporating means, prior systems, the outlet of the restrictor has been connected to the inlet of the evaporating means 30, where the refrigerant evaporates under reduced pressure and is returned to the compressor through the return conduit 32; The compressor 20 i driven by an electric motor 34 under the control of a snap-acting switch means 36 actuated by a fluid pressure system responsive to the temperature of the evaporating means 30.

In such a system, during the idle period, considerable amounts of refrigerant are forced through the restrictor into the evaporator means. After all of the liquid is drawn out of the receiver, warm uncondensed gas from the condenser and receiver may pass through the rev strictor into the evaporating means. This warm gas discharged into the evaporator under such conditions is very detrimental to the efiiciency of the refrigerating system The flooding of the evaporator with liquid refrigerant during the 'idle period may cause trouble at the beginning of the next running period since under such conditions some liquid refrigerant may be drawn from the evaporator into the compressor and thereby damage the compressor. The discharge of liquid refrigerant into the evaporating means during the idle period is also somewhat detri mental to the efficiency of the system, The amount the efiiciency is reduced by this liquid and gas flow during the idle period of the system depends upon the refrigerant used. For example, when sulphur dioxide is used in the system, there is a serious loss in eificiency by this flow during the. idle period. However, when difluoro-tetrafluoro-ethane is used as the refrigerant, this loss is comparatively small and is v 1 shaped member 40 is provided with an entrance 82 connected to the outlet of the restrictor 28 which is provided with a valve seat. The valve needle 44 comes into engagement with theseat during idle periods. This valveneedle 44 is formed as a projection from the end plate provided upon a bellows 48, which has its opposite end connected to and sealed to the lid 42. The

the valve I2 is connected by the conduit 80 to cup-shaped member 40 has a side outlet 50 which is connected to the inlet of the evaporator 30. The lid 42 is provided with a passage 52 extending into the interior of the bellows and provided with external threads which receive a flare nut which connects the passage 52 with tubing 54 which connects to the outlet of the evaporating means 30. The interior of the bellows 48 coritains a relatively light coil spring 58 extending between the lid 42 and the end plate 48 for urging the valve needle 44 into position upon its sea When the switch 38 is opened, and the system is idle, the pressure at the inlet and the outlet of the evaporating means is the same so that the pressure upon the opposite sides of the bellows 48 and its end plate 48 will be the same. Therefore, there will be no opposition to the coil spring 58 which will then hold the valve needle 44 in closed position. When the evaporator 30 becomes warm, the switch 38 is closed, thus placing the system in operation. The compressor will draw evaporated refrigerant from' the evaporator through the return conduit 32. This will cause a gradually increasing pressure diflerential between the inlet and the outlet of the evaporating means and when the compressor approaches full speed, the pressure differential between the exterior and the interior of the be]- lows 48 and its end plate 48 will be suflicient to overcome the force of the spring 58' to hold the valve needle 44 in open position. When the system stops its operation, the pressures on opposite sides of the bellows 48 and its end plate 48 will be again equalized, and the spring 58 will return the valve needle 44 to closed position. In this way, the flooding of the evaporator during idle periods is prevented while the operation of the system during normal running periods is not interfered with.

In Fig. 2, a very similar system is shown with the interchanger 88 where the evaporated refrigerant removes heat from the condensed liquid passing from the conduit 88 to the conduit I0 and is then returned to the compressor through the return conduit 82,

The valve 'I2 is provided with a casing having.

a cup-shaped casing member 84 which receives a second cup-shaped casing member 88 which, together, enclose a cylindrical chamber. The cup-shaped casing member 84 has an inlet passage 88. Connected to the liquid supply conduit I0 is a side outlet passage 90 connected to the I conduit I4 leading to the inlet of the evaporating means I8. The interior of the casing is divided into a chamber 92 connected to the inlet of the evaporating means and a chamber 94' connected to the outlet of the evaporating means. These two chambers are divided by a bellows 98 having an end Plate 98v to which is fastened a needle valve I02 for closing the inlet passage 88. The bellows 98 has its end opposite the end plate connected to and sealed to the rim of the cupshaped casing member 88.

Within the chamber 94 beneath the inlet I04 to which the outlet of the evaporating means I8 is connected by the .conduit I8, there is provided a cup-shaped portion I08 provided with a small aperture I08 in its bottom portion. This cup-shaped portion I08 is formed upon the end of a lever H0 pivoted at II2 to,the cup-shaped casing member 88 and having an arm I I4 ex-I; tending downwardly so as to engage the end portion of the valve needle I02 which extends a considerable distance upon both sides of the end open, and the system is idle, no pressure difthe exception that no restrictor is shown, but' one may be employed in a manner similar'to that shown in Fig. 1 if desired. Inthis system, there is provided a compressor 80 for compressing the refrigerant, a condenser 82 for condensing the refrigerant and a receiver 64 for collecting the condensed refrigerant. The condensed refrigerant is forwarded through a supply conduit 88 to an interchanger 88 and from the interchanger, the condensed refrigerant is forwarded through a conduit 10 to a modified form of valve l2. If desired, the supply conduit 10 may have a sufficiently small cross-section as to serve as a restrictor. The outlet of my valve I2 is connected through a conduit 14 to the inlet of the evaporating means I8. The outlet of the evapcrating means- 18 ,is connected by the conduit 18 to a portion of the valve12 and this portion of ferential will exist upon opposite sides of the bellows 98 and its endplate 98,, and, under such conditions, the weight of the cup-shaped portion I08 will be sufilcient to move-the needle valve I02 into position upon its seat to prevent the flow of liquid refrigerant into the evaporating means.

When there is a demand for refrigeration, the switch I I8 will close, and the compressor will operate, thereby creating a pressure difference upon opposite sides of the bellows 98 and its end plate 98, thereby overcoming the weight of the cupshaped portion I08 to permit the yalve I02 to open. This will allow liquid refrigerant to flow into the evaporating means and will permit such flow until liquid refrigerant or lubricant or a mixture-of liquid refrigerant and lubricant'is' erant and lubricant escape from the cup-shaped portion I08 by evaporation or by passing through the orifice I08 from which it returns to the. com-' pressor through the conduit to the heat interchanger "88 and the conduit 82. The interchanger 88 has a capacity to evaporate refrigerant at a rate exceeding the rate at which refrigerant can pass through the orifice I 08.

scope of the claims which follow.

4. Refrigerating apparatus including liquefy- Any liquid refrigerant discharged from the cupshaped member I06 and passing through the conduit 80 will be evaporated within the heat interchanger so that no liquid. refrigerant will pass into the compressor, and, thus, any damage to the compressor will be prevented. This arrangement will be much more sensitiveto excess refrigerant in the evaporating means than the usual thermostatic expansion valve which has the thermostat bulb' positioned upon the outlet of the evaporating means. Such a thermostat bulb is ordinarily slow to act in case of excess refrigerant because it depends upon changes in temperature which must affect the fluid pressure system which controls the thermostaticexpansion valve. The cup-shaped portion I06 acts instantly, because it 'is directly acted upon by the liquid refrigerant. This valve also keeps the evaporating means filled with liquid refrigerant and thus makes the evaporating means operate at full capacity whenever the system is in operation; and thereby obtains the highest efficiency from the system. i

It should be noted that the bellows in both forms of valves are exposed only to refrigerantv upon both sides.

Therefore, should the bellows leak, no refrigerant will escape from. the system and if the leak is small the operation of the valve will not be materially affected.

It should also be noted that my valve is independent of the evaporator temperature andpressure employed since it merely depends upon the pressure drop between two portions of the evaporator for its operation.

While the form of embodiment of the present invention as herein disclosed constitutes a preferred form, it is to be understood that other forms might be adopted, all coming within th What is claimed is as follows:

1. Refrigerating apparatus including liquefying means and evaporating means, valve means responsive to the pressure differential between two portionsof the evaporating means for controlling the flow of liquid refrigerant from the liquefying means to the evaporating means, and a means forming an elongated orifice located in series circuit relation to the valve means for additionally controlling the flow of liquid refrigerant from the liquefying means to the evaporating means. i

'2. Refrigerating apparatus including liquefying means and evaporating means, valve means responsive to the pressure differential between two, portions of the evaporating means for controlling the flow of liquid refrigerant from the liquefying means to the evaporating means, and a means mechanically responsive to a mechanical aspect of the flow of liquid at the outlet of the evaporating means for controlling the flow of liquid from said liquefying means to said evaporating means.

3. Refrigerating apparatus including a liquefying means and an evaporating means, means forming an elongated orifice for controlling the how of liquid refrigerant from the liquefying means to the evaporating means, and pressure operated means for shutting off the flow of refrigerant through the orifice during idle periods of the liquefying means, said pressure operated means including means responsive to the pressure differential between the two portions of the evaporating means for opening the orifice to the fiow of refrigerant when the liquefying means operates.

ing means and evaporating means, valve means for controlling the flow of liquid refrigerant to the evaporating means, a diaphragm means for operating said Valve means, one side of said diaphragm means being subject to the pressure of the refrigerant at, the inlet of the evaporating means and the other side of said diaphragm means being subject to the pressure of the refrigerant at the outlet of the evaporating means, said valve means being movable to open position when the pressure of the refrigerant at the outlet of the evaporating means is less than the pressure of the refrigerant at the inlet of the evaporating means, and an additional means for the control of the flow of liquid refrigerant from the liquefying means to the evaporating means.

5. Refrigerating apparatus including a closed circuit containing liquefying means and evaporating means, valve means for controlling the flow of refrigerant from the liquefying means to the evaporating means, diaphragm means for moving said valve means to open position when the refrigerant pressure at the outlet is less than the pressure at the inlet of the evaporating means, said diaphragm means upon the side tending to move the valve means to open position being subject to the pressure of the refrigerant at the inlet of the evaporating means, the opposite side of said diaphragm means being subject to the pressure of the refrigerant at the outlet of the evaporating means.

6. Refrigerating apparatus including a closed means upon the side tending to move the valve,

means to open position being subject to the pressure of the refrigerant at the inlet of the evaporating means, the opposite side of said diaphragm means being subject to the pressure of the refrigerant at the outlet of the'evaporating means, and means directly responsive to the flow of liquid refrigerant at the outlet of the evaporating means for closing the valve means to the flow of liquid refrigerant into the evaporating means.

7. A heat transfer means including a closed circuit containing liquefying means and evaporating means,.means for controlling the flow of fluid through said closed circuit, and means including a diaphragm and a movable cup-shaped member mechanically connected to said diaphragm and said controlling means located at the outlet of said evaporating means so as to collect liquid issuing from the evaporating means for regulating said controlling means.

8. A heat transfer means including a closed circuit containing liquefying means and a dry expansion type of evaporating means, an expansion valve located at the inlet of the evaporating means for controlling the flow of fluid into the evaporating means, and means including a .mov-

ation of said expansion valve.

9. A heat transfer means including a closed circuit containing liquefying means and a dry expansion type of evaporating means, an expansion valve located at the inlet of the evaporating means for controlling .the flow of fluid into the evaporating means, and means including a movable cup-shaped member operatively connected to said expansion valve and located beneath the outlet of the evaporating means so as to collect liquid issuing therefrom for controlling the operation of said expansion valve, said cup-shaped member being provided with a small orifice for draining the cup-shaped member at a relatively slow rate. V

10. Refrigerating apparatus including liquefying means and evaporating means, valve means responsive to the pressure differential between two portions of the evaporating means for controlling the flow of liquid refrigerant from the liquefying means to the evaporating means, and means mechanically responsive to the weight of the liquid refrigerant issuing from the outlet of the evaporating means for controlling the flow of liquid from said liquefying means to said evaporating means.

11. A heat transfer means including a closed circuit containing liquefying means and evaporating means, means for controlling the flow of fluid through said closed circuit, a movable cupshaped member located at the outlet of said evaporating means so as to collect liquid issuing from the evaporating means, and means for operatively connecting said cup-shaped member to said controlling means.

MARSHALL W. BAKER. 

